A subtle, but significant tweak to Florida's rules regarding traffic signals has allowed local cities and counties to shorten yellow light intervals, resulting in millions of dollars in additional red light camera fines.

The Florida Department of Transportation quietly changed the state's policy on yellow intervals in 2011, reducing the minimum below federal recommendations. The rule change was followed by engineers, both from FDOT and local municipalities, collaborating to shorten the length of yellow lights at key intersections, specifically those with red light cameras, WTSP TV 10 News of Tampa Bay reports.

While yellow light times were reduced by mere fractions of a second, research indicates a half-second reduction in the interval can double the number of citations — and the revenue they create. Red light cameras generated more than $100 million in revenue last year in about 70 Florida communities, with 52.5 percent of the revenue going to the state.